By 2260 Zathras, 110 years old, was the oldest living caretaker of the Great Machine. During his many years of working with Varn and then Draal, Zathras had studied the machine. Over the years Zathras became so familiar with the machine that he knew things about the machine that even Draal had not yet learned. Draal was also familiar with Babylon 5 and its personnel, learning much about Ambassador Delenn, Ambassador Sinclair, and CaptainJohn Sheridan.

He stayed behind with Sinclair on the journey back to use Babylon 4 as a base of operations during the last Great War, 1000 years in the past. Once Kosh and Ulkesh were satisfied that Sinclair was who he said he was, and entered a Chrysalis, Zathras began wiping the station systems to remove anything that could pinpoint their origins to safeguard the future.[3]

Though he initially appears as a silly and somewhat clumsy creature, Zathras was very dedicated and loyal to the cause as well as wise and technically proficient. His most repeated phrase is "no one listens to Zathras".